Process of making 2, 3-hydroxynaphthoic acid



Patented Nov. 8, 1927.

UNITED STATES. PATENT,

OFFICE. y

mums. camera, or PENNS ruaovn, NEW mnsnr; anrnun. n. anon, on wm- IINGTON, DELAWARE; AND HEBMAHN W. MAHR, PENN S GROVE, NEW JERSEY,

ASSIGNORS TO B. I. DUPONT DE NEMOUBS & COMPANY, OF WILMINGTON, DELA- Wm, A CORPORATION 01 DELAWARE.

.' PBOCESS 01' m G fit-HYDBOXYNAPHTHOIG ACID.

lib-Drawing.

This invention relates to the production of. 2,3-hydroxy-na hthoic acid and comprises heating a eta-naphth presence of carbondioxide at a given 111% temperature, and at a ressure above t e dissociation pressure of t e alkali-metalsalt of 2,1-hydroxy-naphthoic acid at saidglven temperature.

In the reaction of carbon dioxide upon lo alkali-metal: beta naphtholate two isomers are formed,-the alkali-metal salt of the 2,1- droxy-naphthoic acid'and the alkahmeta? salt of the desired 2 ,3 -hydroxy naphthoic acid:

on.-' I

2:1- mm aims-M.

e. Y a.

At temperatures below 170 0., the 2,1-derivat1ve is formed in larger amounts; at higher temperatures the formation of the 2,3-derivative prevails, but much of the 2,1-derivative' ormed at the same time undergoes considerable decomposition resultg in a decrease in the yield of the desired product. 1

We have now discovered that the reaction between carbon dioxide and the beta naphtholate to form 2,3-hydroxy-naphthoic ac1d may be carried on at temperatures well above 170 0., and the decomposition of the 2,1-derivat-ive prevented, by maintaining the carbon dioxide at a pressure above the decom osition-pressure of the 2,1-hydroxynap thoate at the temperature prevailing during the reaction. By preventing the decomposition of the 2,1-derivative the yield of 2,3-derivative is'increased since the latter is produced from the former by isomerization.

By decomposition-pressure we mean the pressure of carbon dioxide below which the 2,1-hydroxy-naphthoate begins to decompose at the temperature employed. The preferred tem erature ran 0 for the formation of the 2,3-Eydroxy-nap thoic is from about 225 to 250 C. The decompositiompressure curve throughout this range for the 2,1-hydroxy late in the me a... February as, 1924. Serial no. 894,785. g

naphthoate may beindicated by the followmg table:

. Dissociation Temperature. pressure.

225 C. 375 lbs. sq. inch. 235 C. 450 lbs. sq. inch.- 250 C. 600 lbs. sq. inch.

above set forth, we observed, for example,

that when the reaction of dry carbon ,di-.

oxide .upon anhydrous alkali-metal, betanaphtholate, and the conversion of the resultin alkali-metal naphthol-carbonate to the a ali metal salt ofthe 2,1- and 2,3-hydroxy-na hthoates, was carried out under a carbon ioxide presiure of 500 lbs. per square mch or highe at a temperature of 225 0., a much greater yield of the desired 2:3-derivative was obtained than at the lower pressures; also, that 'the proportionate amount of decomposition products derived therefrom was much lower.

The new process may be further illustrated by the following example, to which however the invention is not limited: Example: In a suitable high pressure apparatus, e uipped with a stirrer and appropriate evlce for measuring temperatures and pressures, 500 parts of powdered anhydrous sodium betanaphtholate are placed. The naphtholate is well agitated during which dry carbon dioxide gas is iorced in untila pressure of 500 lbs. or greater per square inch is reached. The pressure of 500 lbs. and temperature of 225 C. to 235 C. are'maintained' for about hours, stirring constantly. After cooling, the contents of the apparatus are extracted with water and the 2,3-hydr0xy-na hthoic acid recovered by well known metho s.

The various conditions under which the 5 operation is. carried out may be varied withoperation may be carried to any .point short the decomposition temperature of the desired product. ,It is obvious that, in a process of manufacturing 2,3-hydroxy-naphthoates, it is undesirable to operate at such temperatures as will decompose the desired Cproduct with consequent diminution in yiel We claim:

1. The process of producing 2,3-hydroxynaphthoic acid which comprises heating a beta-naphtholate in contact with carbon dioxide at a temperature above 180 C. while maintaining the pressure of said carbon dioxide above the decomposition-pressure of 2,1-hydroxy-naphthoate at the temperatures prevailing during the reaction, said temperatures being below that at which an undesirable chemical change occurs in the 2,3- hydroxy-naphthoate.

2. A process as setforth in claim 1 in which the reaction between the carbon dioxide and the beta-naphtholate is carried on at temperatures between 200 and 300 C. 3. The rocess of producing the 2,3-h droxy-nap thoic acid which comprises su jecting an alkali-metal beta-naphtholate to I 'naphthoic acid which com masses the action of carbon dioxide at a temperature of from about 225 C. to 250 0., the pressure of the carbon dioxide being maintained sufliciently high to prevent appreciable decomposition of any 2,1-hydroxy-naphformed in the course of 5. The process of producing 2,3-hydroxyrises heating a material comprising an al ali-metal betanaphtholate in the presence of carbon dioxide at temperatures between about 200 and 300 C., and maintaining the pressure of the carbon dioxide so high as to inhibit decomosition at said temperatures of any alkalimetal 2,1-hydroxy-naphthoate formed.

In testimony whereof we afiix our signatures.

WILLIAM S. GALCOTT. ARTHUR R. HITCH. HERMANN W. MAHR. 

